On rotary press folding machines, a generally cylindrical cutting drum having a pair of cutting blades is positioned adjacent to a folding drum. The blades of the cutting drum cut a web of paper having an image imprinted thereon into sections of a predetermined length, which are then folded by the folding drum in a manner well known in the art.
Preferably, the cutting drum blades are adjustable, making it possible to run the folding machine in both "straight" and "collect" modes. When the press is operated in "straight" mode, the cutting drum blades are oppositely disposed on the cutting drum. Thus, the drum cuts two paper sections of equal length per revolution. The sections have an identical image, making a continuous run possible. By comparison, when operating in "collect" mode, one of the cutting drum blades is moved circumferentially, enabling the cutting drum to cut one longer section and one shorter section per revolution. The sections, having different images imprinted thereon, are then collected before folding, thus precluding a continuous run.
A variety of devices have been employed in order to provide for the adjustment of the cutting blades. One such approach is to adjust the position of the blades using one or more spacers. The position of the blade is then fixed using a wedge to lock the blade in place. Unfortunately, in order to i adjust the position of the blades, the press must be stopped, and the wedges and spacers must be extracted and re-installed. Such a system is labor intensive and time consuming, and does not permit stepless adjustment of the cutting blades.
Another prior art device is disclosed in U.S. Pat. No. 5,017,184 issued to Takahori et al. The Takahori device uses an outer cylinder having a first cutting blade and an inner cylinder housed within and rotatable relative to the outer cylinder and having a second cutting blade which protrudes from a gap in the outer cylinder. Unfortunately, in addition to other shortcomings the range of adjustability is limited due to the inner/outer cylinder construction.
Accordingly, there exists a need for an improved cutting bar for use with a rotary press folding machine.